Advanced scripting with JShell

What are the limits of JShell? There is so much you can do with this tool, and you are virtually only limited by your imagination and programming abilities.

Let's look at an advanced code base that can be used to compile and run Java programs from a JShell script:

    import java.util.concurrent.*
    import java.util.concurrent.*
    import java.util.stream.*
    import java.util.*

    void print2Console(String thetext) 
    { 
      System.out.println(thetext); 
      System.out.println("");
    }

    void runSomeProcess(String... args) throws Exception 
    { 
      String theProcess = 
        Arrays.asList(args).stream().collect(
         Collectors.joining(" ")); 
        print2Console("You asked me to run: '"+theProcess+"'"); 
        print2Console(""); 
        ProcessBuilder compileBuilder = new 
          ProcessBuilder(args).inheritIO(); 
        Process compileProc = compileBuilder.start(); 
        CompletableFuture<Process> compileTask =
         compileProc.onExit(); 
        compileTask.get();
    }

    print2Console("JShell session launched.")
    print2Console("Preparing to compile Sample.java. . . ")

    // run the Java Compiler to complete Sample.java
    runSomeProcess("javac", "Sample.java")
    print2Console("Compilation complete.")
    print2Console("Preparing to run Sample.class...")

    // run the Sample.class file
    runSomeProcess("java", "Sample")
    print2Console("Run Cycle compete.")

    // exit JShell
    print2Console("JShell Termination in progress...)
    print2Console("Session ended.")

    /exit

As you can see with this script, we created a runSomeProcess() method and can use it to explicitly compile and run external Java files.